I'm curious. How is it that you know it is only infertility that will result from such species crosses? It would seem that nailing down so much, saying it can ONLY be one thing that would be affected, would be hard to support
Actually, I didn't say that *only* infertility will result if the chromosome numbers are different, merely that hybrids of parents with different chromosome numbers will necessarily be infertile (due to lack of homolgous chromosome pairing during meiosis). You're correct in stating that a wide number of effects are possible, and that prediction of these effects without detailed knowledge of the animal's genome is impossible. But since the mechanism of infertility in hybrids is known, and chromosome numbers of various species are well known, it's possible to predict
a priori that this particular pairing would result in infertile offspring, if any offspring at all.
That's a point of contention and not a view that is held universally. Although given your other posts on this and similar subjects, I'd guess you meant it in the abstract sense- applying the morality to the individual performing the action rather than the action itself. Not everyone is capable of making the distinction though and given the inherent likelyhood of contamination... Well- some people feel pretty strongly that there's something very wrong with hybridization.
Actually, what I mean is that I have seen no arguement based on actual genetics that hybridization is somehow wrong or harmful when between closely related species. Hybrids between distantly-related species can cause trouble, as the developmental pathways have likely diverged somewhat, but between closely related species, there is no
a priori reason to conclude that the hybrid will be of poor health (and, in fact, considerable reason to suspect it will be healthier).
An individual's personal views on nature and such may lead them to view hybridization as unethical, but it is important to remember that this view is based on personal opinion and beliefs, not genetics. Many of the objections I've seen rely on misunderstandings or outdated information on genetics, evolution, speciation, and what consitutes a 'species' (which in reality is nowhere near as clean as Mayr's definition). I have no objection to people thinking it's wrong for non-genetic reasons related to their personal philosophies, but in such situations one should always remember that one's own personal views are just that rather that absolute facts.
Henry
